Semiconductor devices are typically tested after manufacturing to make sure that a functional semiconductor device has been formed. Other sorts of tests, such as classifying a functioning semiconductor device according to speed, etc., is usually performed also using the same or similar equipment.
One type of equipment has a probe card with probe tips. FIG. 1 includes an illustration of a portion of a probe card 10 that includes a base 14 and a probe tip 12. The base 14 is typically an insulating material, and the probe tip 12 is typically a conductor, such as a metal-containing material. The probe tip 12 includes a beam section 122 and a tip section 124. The beam section forms an angle .theta. with respect to the bottom surface of the base 14. Angle .theta. is typically 3 degrees. Angle .OMEGA. is formed between the beam section 122 and the tip section 124 and in a range of 103-106 degrees.
FIG. 2 includes another type of probe card 20 that includes a base 24 with an opening 26. The probe tip 22 includes a beam portion 222 and a tip portion 224 that are two discrete portions. Probe tip 22 further includes a bump 226 that allows the probe tip to move a limited distance in a vertical direction because the combination of the tip portion 224 and the bump 226 is larger than the diameter of the opening 26.
The probe tips of FIG. 1 or 2 are used to scrape a portion of a pad of a semiconductor device to break through an oxide on the pad. If the pad includes aluminum, the aluminum forms aluminum oxide when exposed to air. Aluminum oxide is an insulator and must be broken through in order to probe properly the semiconductor device.
FIG. 3 includes an illustration of the probe card 20 during the probing of a semiconductor device 30. The semiconductor device 30 includes a base 32 that includes an insulating layer, a pad 34, and a passivation layer 36. When the semiconductor device 30 is tested, the semiconductor device 30 is typically moved toward the base 24 of the probe card 20. When the probe tip 22 contacts the semiconductor substrate 30, the probe tip 22 moves upward until the bump 226 hits the base 24.
After the bump 226 hits the base 24, the tip section 224 below the base 24 is deflected which causes the end of the probe tip 24 to move along the pad 34. The end of the probe tip 24 typically moves one unit of distance along the pad 34 for every ten units or less of vertical movement of the substrate. As can be seen in FIG. 3, the probe tip 22 can hit the passivation layer 36 causing a piece 362 of the passivation layer 36 to break. When this piece 362 is removed, an edge 38 of the pad 34 is now exposed which may allow moisture or other contaminants to migrate beneath the passivation layer. Such a result is typically not desired due to problems with reliability. The probe tip 12 of FIG. 1 suffers from a similar problem because the probe tip can move too far and break off a piece of passivating material.
A need exists for testing integrated circuits in a nondestructive manner that allows accurate probing. A need also exists for testing semiconductor devices with small pad pitch.